Pedicle screw with screw-in aid

Abstract

A bone screw includes a receiving sleeve having a sleeve wall which forms a seat for a longitudinal support for the surgical connection of adjacent bone screws. The bone screw includes an internal thread. A thread turn of the internal thread has a widened lead-in region on the thread lead-in side.

The invention claimed is: 
     
       1. A bone screw comprising:
 A. a screw head; and 
 B. a receiving sleeve or tulip provided on the screw head, the receiving sleeve or tulip having a proximal-most end and a distal-most end and comprising:
 i. two sleeve flanks, each sleeve flank provided with an internal thread; and 
 ii. a seat for a longitudinal support for surgical connection of adjacent bone screws, the seat formed between the two sleeve flanks, 
 
 the internal thread of at least one of the two sleeve flanks comprising a thread entry, a thread turn and a thread lead-in side, and 
 the thread turn comprising a widened lead-in region at the thread entry and a residual thread turn, the widened lead-in region on the thread lead-in side being widened relative to the residual thread turn to facilitate correct attachment of a clamp screw or set screw to the receiving sleeve or tulip, 
 the widened lead-in region having a first flank, the first flank being inclined in a circumferential direction relative to a second flank in a further run of the residual thread turn outside the widened lead-in region, 
 the internal thread of the at least one of the two sleeve flanks formed between the proximal-most end and the distal-most end of the receiving sleeve or tulip, and 
 the thread turn and the widened lead-in region beginning below a proximal-most end of the receiving sleeve or tulip. 
 
     
     
       2. The bone screw according to  claim 1 , wherein the widened lead-in region is widened in an axial direction. 
     
     
       3. The bone screw according to  claim 1 , wherein the first flank rises into said internal thread of said at least one of the two sleeve flanks. 
     
     
       4. The bone screw according to  claim 3 , wherein an inclination of the first flank is flatter than an inclination of the second flank, wherein the inclination of the first flank corresponds to 0.5 times to 0.9 times the inclination of the second flank. 
     
     
       5. The bone screw according to  claim 1 , wherein a cross-sectional area in a radial direction of the thread turn at the thread entry corresponds to 1.7 times to 1.2 times a cross-sectional area of the thread turn outside the widened lead-in region. 
     
     
       6. The bone screw according to  claim 1 , wherein the widened lead-in region extends in a circumferential direction over a radial portion through an angle of between 20° and 135° relative to an axis of the internal threads. 
     
     
       7. The bone screw according to  claim 1 , wherein the internal thread of each of the two sleeve flanks is an undercut thread, or wherein the thread turn has a T-shaped or L-shaped cross-section. 
     
     
       8. The bone screw according to  claim 1 , wherein a thickness in an axial direction of a thread land located between the widened lead-in region and an adjacent thread turn is reduced as compared to a thickness of a thread land between adjacent thread turns by less than 50%. 
     
     
       9. The bone screw according to  claim 1 , wherein the receiving sleeve or tulip is formed integrally with the bone screw, or wherein the receiving sleeve or tulip is arranged to be positioned relative to the bone screw on the bone screw. 
     
     
       10. A method of manufacturing a bone screw according to  claim 1 , wherein the widened lead-in region is formed by milling. 
     
     
       11. The bone screw according to  claim 1 , wherein the thread entry forms a ramp configured to guide or lift a clamp screw or set screw initially obliquely attached or tilted during attachment, when the clamp screw or set screw is further screwed into the thread turn at the thread entry, and to align the clamp screw or set screw coaxially with respect to the internal thread of each sleeve flank of the receiving sleeve or tulip. 
     
     
       12. The bone screw according to  claim 1 , wherein the widened lead-in region is widened in a radial direction. 
     
     
       13. The bone screw according to  claim 1 , wherein said internal thread of the at least one of the two sleeve flanks comprises a first thread turn portion and a third thread turn portion, the first thread turn portion comprising the widened lead-in region at the thread entry, and the third thread turn portion having a constant cross section. 
     
     
       14. The bone screw according to  claim 1 , wherein the bone screw head and the receiving sleeve or tulip are formed as one-piece. 
     
     
       15. The bone screw according to  claim 1 , wherein the receiving sleeve or tulip engages the screw head. 
     
     
       16. The bone screw according to  claim 1 , wherein the internal thread further comprises a second thread turn and a third thread turn, the second thread turn and third thread turn having a constant cross-section. 
     
     
       17. A bone screw comprising:
 A. a screw head; and 
 B. a receiving sleeve or tulip provided on the screw head, the receiving sleeve or tulip comprising:
 i. two sleeve flanks, each sleeve flank provided with an internal thread; and 
 ii. a seat for a longitudinal support for surgical connection of adjacent bone screws, the seat formed between the two sleeve flanks, 
 
 the internal thread of at least one of the two sleeve flanks comprising a thread entry, a thread turn and a thread lead-in side, and 
 the thread turn comprising a widened lead-in region at the thread entry and a residual thread turn, the widened lead-in region on the thread lead-in side being widened relative to the residual thread turn to facilitate correct attachment of a clamp screw or set screw to the receiving sleeve or tulip, 
 the widened lead-in region having a first flank, the first flank being inclined in a circumferential direction relative to a second flank in a further run of the residual thread turn outside the widened lead-in region, and 
 the receiving sleeve or tulip being formed integrally with the screw head. 
 
     
     
       18. A bone screw comprising:
 A. a screw head; and 
 B. a receiving sleeve or tulip provided on the screw head, the receiving sleeve or tulip comprising:
 i. two sleeve flanks, each sleeve flank provided with an internal thread; and 
 ii. a seat for a longitudinal support for surgical connection of adjacent bone screws, the seat formed between the two sleeve flanks, 
 
 the internal thread of at least one of the two sleeve flanks comprising a thread entry, a thread turn and a thread lead-in side, 
 the thread turn comprising a widened lead-in region at the thread entry and a residual thread turn, the widened lead-in region on the thread lead-in side being widened relative to the residual thread turn to facilitate correct attachment of a clamp screw or set screw to the receiving sleeve or tulip, 
 the widened lead-in region having a first flank, the first flank being inclined in a circumferential direction relative to a second flank in a further run of the residual thread turn outside the widened lead-in region, and 
 the thread turn comprising an upper portion and a lower portion, the widened lead-in region extending upwardly from the lower portion of the thread turn.